Help with this gardenia, please.

7 years ago

This plant has been in the ground since May. I didn't test the soil. All I know is that it's clay and drains very well.

During the awful heatwaves we had in July and August, this gardenia was one of the very few plants in my garden that did not get sun scorching at all, not even one leaf. I was very surprised and happy that I somehow managed to keep it alive and well. However, come September, the leaf yellowing started. Some leaves also have some rusty patches.

I have not been overwatering it.

I probably could do better when it comes to fertilizing the plants in my garden but I've been given them SuperThrive every couple of weeks (as per directions on label) and, last week I tried fertilizing with Masterblend (also as per directions). However, this gardenia was doing great on SuperThrive and had already started to yellow before I applied Masterblend.

Featured Answer

gardengal48 (PNW Z8/9)

7 years ago

It's a bit late now but you probably should have tested your soil :-) Gardenias require a pretty acidic soil (5.0 to 6.5), which is something that I don't think is very common with SoCal soils (same with your irrigation water - usually on the alkaline side of the scale). The leaves are yellowing due to chlorosis or lack of ability to access iron. And this is very common in soils that have too high a pH.

There are various ways to get around this, including dosing with chelated iron. But I'd get my soil tested and after determining the soil pH, adjust as necessary to lower pH to an appropriate level. Agricultural sulfur is the usual method but it will be something you will need to attend to periodically, as the soil will be inclined to drift back to its original/natural pH.

Using a fertilizer for acid loving plants can help - most have a soil acidifier included as well. Something like Espoma Holly Tone or Miracid (aka, Miracle Gro for Acid Lovers). The MG will work faster and because it includes iron chelate, you will see leaf 'greening' much sooner.

btw, SuperThrive is not fertilizer!! It is just a plant "tonic" of dubious efficacy comprised of various plant growth hormones and vitamins. But it does not supply basic plant nutrients as a fert will and will do nothing special for the gardenia.

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Comments (9)

ken_adrian Adrian MI cold Z5
7 years ago
its planted awful close to the cement foundation ... i wonder if that means anything ... does anything else planted that close to such.. struggle???

ken
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gardengal48 (PNW Z8/9)
7 years ago
Planting that close to a concrete foundation will definitely have an impact!! Concrete leaches lime indefinitely and that will alter soil pH, sometimes to unfavorable levels. Virtually any acid loving plant will be stressed if sited close to concrete and you will need to take steps to mitigate the problem.
Bleu (Zone 9b - So Cal)
Original Author
7 years ago
Thanks for the advice, gardengal.

Around here most houses have flowerbeds along house walls. Some are even in between the wall and a cement walkway and most of these beds are less than 2' wide yet I have seen all kinds of mature and young acid-loving plants in those beds doing just fine. Maybe the people who maintain those gardens are mitigating the lime leaching problem. I wouldn't know.

I will give the Miracid a try. I hope it helps because all my flowerbeds are along walls.
BlueSky Susan (10b-24)
7 years ago
Bleu, you probably already are aware of this but just in case not - you don't have to send away for a Ph test - lots of the cheapie water probes also have a PH scale. I think you need to get the two prong ones.

My gardenia, planted in fairly neutral soil, responds well to "soil acidifier", which the local nursery sold me. I also amended the soil with "Gardenia/Azalea mix" before planting and give it "Gardenia and Azalea" fertilizer. That combo, with the acidifier and the fertilizer applied about once a month, seems to keep it happy. Those two might be duplicating each other, I'm not sure - but my plant likes getting both.
Bleu (Zone 9b - So Cal) thanked BlueSky Susan (10b-24)
ken_adrian Adrian MI cold Z5
7 years ago
last modified: 7 years ago
what i am trying to say.. another way ... is separate the process between a fert.. and a soil amendment ...a fert ....

its been so long since i did this.. i am sure others can speak to such ... like ammonium sulfate .. and perhaps sulphur .. i think ...

what i am trying to say.. another way ... is seperate the process between a fert.. and a soil amendment ...

i think part of it.. is that i am always leery.. with a product you have to apply many times a season .. to the profit of the seller... as compared to changing the soil .. with less applications per year ... im not really in this.. to buy a boat for the fert salesman .. .lol ...

all that said.. it might be easier to grow it in a pot ... if your soil is so far out of wack in regard the pH .... akin to many peeps who grow blueberries in pots for said reason ....

ken

houzz screwed the format again .. i will TRY to recreate it .. i need to figure out what the first two paragraphs were ... and im pissed and blanking right now.. lol ...
Bleu (Zone 9b - So Cal) thanked ken_adrian Adrian MI cold Z5
Bleu (Zone 9b - So Cal)
Original Author
7 years ago
BlueSky Susan,

Thanks for the tips. Yes, I've seen the soil kits but I always forget to pick one up. And I am a terrible gardener who never thinks of testing the soil before buying and planting plants. So far I've been lucky that the plants I put in the ground here are doing well, except for this gardenia. Dumb luck, I guess.

I gave the gardenia a good drink of Miracid a couple of days ago. Will repeat as per directions.

What soil acidifier are you using? Is it liquid or granular?
Bleu (Zone 9b - So Cal)
Original Author
7 years ago
Ken, I get what you are saying and I tend to think that way too. The only reason I am not putting the gardenia back in a pot is that potted plants here (south exposure) don't do very well during the summer - July and August felt like a continuous heatwave, it was awfully hot.
socalnolympia
7 years ago
last modified: 7 years ago
Sometimes constant cold to cool temperatures can make it difficult for the plant to absorb enough iron from the soil, and leads to a nutrient deficiency.